A treatment method for recycled solvents in the preparation process of ametryn

Abstract

The present invention relates to the technical field of solvent recovery, and specifically discloses a treatment method for recovering solvents in the preparation process of ametryn. In the present invention, water is added to the recovered isopropanol solvent, so that the solubility of dimethyldisulfide in isopropanol rapidly decreases, thereby causing dimethyldisulfide to precipitate out in isopropanol, and a dimethyldisulfide by-product is recovered. Then, sodium chloride is added to the isopropanol aqueous solution from which dimethyldisulfide has been recovered to separate isopropanol from water. Subsequently, the obtained crude isopropanol is adsorbed by a specific adsorption resin, effectively adsorbing and removing various sulfur-containing by-products contained in isopropanol, and obtaining odorless isopropanol. The treatment method for recovering isopropanol provided by the present invention not only effectively removes various odor substances in the recovered isopropanol solvent, but also obtains a dimethyldisulfide by-product with higher added value, having high economic and environmental benefits and high promotion and application value.

Description

Technical Field

[0001] The present invention relates to the technical field of solvent recovery, and particularly relates to a treatment method for recovered solvents in the preparation process of ametryn. Background Art

[0002] Ametryn, chemical name: 2-ethylamino-4-isopropylamino-6-methylthio-1,3,5-triazine, English name: ametryn, molecular formula: C9H 17 N5S, molecular weight: 227.33, chemical structural formula is as follows. Its pure product is colorless crystals, melting point 84 - 86 °C (recrystallized from petroleum ether), and is easily soluble in organic solvents. Ametryn is a triazine type systemic conduction selective herbicide with a rapid herbicidal effect. It is a typical photosynthesis inhibitor and can be applied before or after emergence. It is used to control grassy weeds and broad-leaved weeds in crops such as corn, sugarcane, pineapple, banana, and citrus. It also has a certain inhibitory effect on some perennial weeds, has a broad herbicidal spectrum and a long residual effect, and is a widely used herbicide at present.

[0003]

[0004] Currently, the domestic industrial production method of ametryn generally uses atrazine and excessive sodium methyl mercaptide for high-temperature synthesis reaction in isopropanol solvent. After the reaction, oil-water separation is carried out. The oil phase is distilled to obtain isopropanol solvent and ametryn, and the recovered isopropanol solvent is recycled to the synthesis process for reuse. However, with the recycling of isopropanol solvent, the malodorous smell of the obtained ametryn product becomes stronger and stronger, which not only affects the production environment, but also directly affects the promotion and sales of ametryn products, and also limits the recycling times of isopropanol. Therefore, there is an urgent need to develop a treatment method for isopropanol that can realize the reuse of isopropanol and does not significantly increase the malodorous smell of ametryn products. Summary of the Invention

[0005] Aiming at the problem that the repeated use of the recovered isopropanol solvent in the existing ametryn production process will significantly increase the malodorous smell of ametryn products, the present invention provides a treatment method for recovered solvents in the ametryn preparation process. It mainly recovers dimethyl disulfide in the recovered isopropanol, and then adsorbs the isopropanol containing the recovered dimethyl disulfide through a specific resin to obtain odorless isopropanol. This not only realizes the recycling of isopropanol, but also significantly improves the product quality of ametryn, and has high economic and environmental benefits.

[0006] To solve the above technical problems, the technical solution provided by the present invention is:

[0007] A treatment method for recovered solvents in the ametryn preparation process, comprising the following steps:

[0008] Step a: Add water to the recycled isopropanol solvent, mix evenly, let stand, and separate the liquid to obtain a dimethyl disulfide oil phase and an isopropanol aqueous solution.

[0009] Step b: Add sodium chloride to the isopropanol aqueous solution, mix evenly, let stand, and separate the liquid to obtain a sodium chloride aqueous solution and crude isopropanol.

[0010] Step c: Pass the crude isopropanol through HYA109 macroporous adsorption resin for adsorption to obtain refined isopropanol.

[0011] During the reaction of sodium methyl mercaptide with atrazine, many sulfur-containing by-products will be generated, such as dimethyl disulfide, methyl sulfide, methyl mercaptan, and other sulfur-containing by-products. These sulfur-containing by-products are dissolved in isopropanol. As the number of times of recycling isopropanol increases, the accumulation of sulfur-containing by-products in the product also increases, resulting in an increasingly strong stench in the ametryn product. Conventional distillation methods simply cannot achieve the full removal of complex odor substances in isopropanol. Moreover, due to the high solubility of sulfur-containing compounds such as dimethyl disulfide in isopropanol, it is very difficult to fully remove various sulfur-containing by-products from isopropanol through solvent extraction methods.

[0012] The treatment method for the recycled solvent in the ametryn preparation process provided by the present invention is as follows: By adding water to the recycled isopropanol solvent, the solubility of dimethyl disulfide in isopropanol rapidly decreases, so that dimethyl disulfide precipitates out of isopropanol, and the dimethyl disulfide by-product is recovered. Then, sodium chloride is added to the isopropanol aqueous solution from which dimethyl disulfide has been recovered to separate isopropanol from water. Next, the obtained crude isopropanol is adsorbed by a specific adsorption resin to effectively and fully adsorb and remove various sulfur-containing by-products contained in isopropanol, obtaining odorless isopropanol. The treatment method for the recycled isopropanol provided by the present invention not only effectively removes various odor substances in the recycled isopropanol solvent, realizes the recycling of isopropanol, but also obtains a dimethyl disulfide by-product with higher added value. In addition, no other organic solvents are introduced in the whole treatment process, and high-temperature rectification treatment is not required, meeting the requirements of green environmental protection and energy conservation and consumption reduction, and having high economic and environmental benefits and high promotion and application value.

[0013] It should be noted that the recycled isopropanol solvent is prepared through the following process: Atrazine and sodium methyl mercaptide are subjected to a high-temperature reaction in an isopropanol solvent. After the reaction is completed, oil-water separation is carried out, and the oil phase is distilled to obtain the recycled isopropanol solvent.

[0014] Preferably, in step a, the addition amount of water is 1 / 3 to 2 / 3 of the mass of the recycled isopropanol solvent.

[0015] Adding the above preferred amount of water to the recycled isopropanol solvent can fully precipitate dimethyl disulfide from isopropanol and improve the recovery rate of dimethyl disulfide.

[0016] Preferably, in step a, the standing time is 1 h to 2 h.

[0017] The preferred standing time can ensure that dimethyl disulfide fully precipitates from isopropanol.

[0018] Exemplarily, in step a, after adding water to the recycled isopropanol solvent, stir and mix for 2 h to 3 h, and then stand for liquid separation.

[0019] Preferably, in step a, it further includes: distilling the dimethyl disulfide oil phase to obtain a dimethyl disulfide product.

[0020] Distilling the secondary dimethyl disulfide oil phase obtained by liquid separation can obtain a dimethyl disulfide product with a purity of more than 95%. The obtained dimethyl disulfide product can be directly sold, improving the enterprise's income and realizing the resource utilization of waste. In the present invention, no special limitation is made on the above distillation conditions, and the specific distillation conditions can be obtained by routine adjustment by those skilled in the art.

[0021] Preferably, in step b, the mass ratio of sodium chloride to the recycled isopropanol solvent is 0.03 to 0.05:1.

[0022] Preferably, in step b, the standing time is 1 h to 2 h.

[0023] The preferred addition amount of sodium chloride and the standing time are beneficial to the full separation of isopropanol and water, reducing the water content in isopropanol, thereby improving the efficiency of subsequent adsorption treatment.

[0024] Furthermore, the sodium chloride solution obtained by liquid separation in step b can be simply purified, concentrated, and dried to obtain a sodium chloride by-product with a relatively high purity (about 95%), which can be directly sold as an industrial sodium chloride product.

[0025] Preferably, in step c, the feeding flow rate of the crude isopropanol is 250 kg / h to 350 kg / h.

[0026] The preferred feeding flow rate of the crude isopropanol can shorten the treatment time and improve the treatment efficiency on the premise of considering the adsorption removal effect.

[0027] Preferably, in step c, a multi-stage series-connected HYA109 macroporous adsorption resin device is used for adsorption.

[0028] More preferably, in step c, a two-stage series-connected HYA109 macroporous adsorption resin device is used for adsorption.

[0029] The HYA109 macroporous adsorption resin used in the present invention is purchased from Xi'an Hanyu Resin Technology Co., Ltd. Its unique resin filler, pore volume and pore diameter can fully remove various sulfur-containing odor substances in isopropanol, significantly reduce the malodorous smell of isopropanol, so that the recycled isopropanol can be recycled into the synthesis process of atrazine, significantly reduce the pungent smell of atrazine, and improve the product market competitiveness of the enterprise.

[0030] It should be noted that, verified by the inventor, when the content of sulfur-containing by-products in isopropanol is less than 200 ppm, it will basically not have an adverse effect on the atrazine product and can be recycled; if the content of sulfur-containing by-products in isopropanol is detected to be higher than 200 ppm after multiple cycles of recycling, the recycled isopropanol solvent will be treated according to the above process. After treatment, the content of sulfur-containing by-products in the isopropanol solvent can be reduced to less than 20 ppm and can be recycled into the synthesis process of atrazine again.

[0031] The method for treating the recycled solvent in the atrazine preparation process provided by the present invention has simple process operation, low energy consumption, and will not cause secondary pollution to the environment. At the same time, high-value-added by-products of dimethyl disulfide and sodium chloride products are obtained through the treatment, realizing the resource utilization of the recycled isopropanol solvent, enabling isopropanol to be recycled, reducing the environmental protection treatment cost, having high economic and environmental benefits, and having extremely high promotion value. Detailed implementation manners

[0032] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0033] The components in the recycled isopropanol solvent are complex and there are many interfering factors. Coupled with the high solubility of sulfur-containing compounds in isopropanol, the existing purification methods are not ideal when applied to the removal of various sulfur-containing compounds in isopropanol. Therefore, how to effectively remove various sulfur-containing compounds in the recycled isopropanol solvent is the key and difficulty in realizing the multiple reuse of isopropanol at present.

[0034] The macroporous adsorption resin in the following examples and comparative examples is purchased from Xi'an Hanyu Resin Technology Co., Ltd.

[0035] The recycled isopropanol solvents used in the following examples and comparative examples are all prepared by the following process: atrazine and sodium methyl mercaptide are subjected to a high-temperature reaction in an isopropanol solvent. After the reaction is completed, oil-water separation is carried out, and the oil phase is distilled to obtain the recycled isopropanol solvent.

[0036] In the following examples, the content of odor substances in the isopropanol solvent is detected by gas chromatography, and the detection conditions are as follows:

[0037] Gas chromatograph: Agilent 7820A;

[0038] Chromatographic column: Rxi-5ms, 60m * 0.25mm * 0.25μm;

[0039] Injection temperature: 150°C;

[0040] Detector temperature: 250°C;

[0041] Injection program: Maintain at 50°C for 10 min;

[0042] Split ratio: 10:1;

[0043] Flow rate: 2 mL / min;

[0044] Headspace heating oven temperature: 80°C, heating time 10 min;

[0045] Injection method: Headspace injection.

[0046] Sample preparation:

[0047] Weigh approximately 0.02 g of dimethyl disulfide reference substance, methyl sulfide reference substance, and methanethiol reference substance respectively, accurately weigh them, place them in a headspace vial, inject for analysis, and record the chromatogram;

[0048] Weigh approximately 0.3 g of isopropanol solvent, accurately weigh it, place it in a headspace vial, inject for analysis, and record the chromatogram.

[0049] Weigh approximately 1 g of ametryn product, accurately weigh it, place it in a headspace vial, inject for analysis, and record the chromatogram.

[0050] According to the external standard method, calculate the contents of dimethyl disulfide, methyl sulfide, and methanethiol in the isopropanol solvent.

[0051] To better illustrate the present invention, further examples are given below by way of examples.

[0052] Example 1

[0053] A method for treating recycled solvent in an ametryn preparation process, comprising the following steps:

[0054] Add 335 kg of water to the isopropanol solvent recovered from the preparation process of 1000 kg of ametryn, stir for 2 h, let it stand for 1.5 h for layer separation, open the liquid separation valve, and separate the lower oil layer into the crude dimethyl disulfide tank. Then, under stirring conditions, add 30 kg of sodium chloride to the remaining upper layer of isopropanol aqueous solution, stir for 2 h, let it stand for 1 h for layer separation, open the liquid separation valve, and separate the lower sodium chloride aqueous solution into the crude sodium chloride tank. Transfer the upper layer of crude isopropanol to the crude isopropanol storage tank. When the storage volume of crude isopropanol accumulates to 3 t, pump the crude isopropanol into the adsorption system filled with HYA109 macroporous adsorption resin at a flow rate of 300 kg / h, collect the effluent, and obtain refined isopropanol. Use gas chromatography to detect that the content of odor substances (dimethyl disulfide, methyl sulfide, and methanethiol) in the refined isopropanol is 10 ppm.

[0055] Example 2

[0056] A method for treating the recovered solvent in the preparation process of ametryn, comprising the following steps:

[0057] Add 400 kg of water to the isopropanol solvent recovered from the preparation process of 1000 kg of ametryn, stir for 3 h, let it stand for 2 h for layer separation, open the liquid separation valve, and separate the lower oil layer into the crude dimethyl disulfide tank. Then, under stirring conditions, add 40 kg of sodium chloride to the remaining upper layer of isopropanol aqueous solution, stir for 3 h, let it stand for 1 h for layer separation, open the liquid separation valve, and separate the lower sodium chloride aqueous solution into the crude sodium chloride tank. Transfer the upper layer of crude isopropanol to the crude isopropanol storage tank. When the storage volume of crude isopropanol accumulates to 3 t, pump the crude isopropanol into the adsorption system filled with HYA109 macroporous adsorption resin at a flow rate of 250 kg / h, collect the effluent, and obtain refined isopropanol. Use gas chromatography to detect that the content of odor substances (dimethyl disulfide, methyl sulfide, and methanethiol) in the refined isopropanol is 15 ppm.

[0058] Example 3

[0059] A method for treating the recovered solvent in the preparation process of ametryn, comprising the following steps:

[0060] Add 650 kg of water to the isopropanol solvent recovered from the preparation process of 1000 kg of ametryn, stir for 2.5 h, let it stand for 1 h to separate layers, open the separation valve, and divide the lower oil layer into the crude dimethyl disulfide tank. Then, under stirring conditions, add 50 kg of sodium chloride to the remaining upper isopropanol aqueous solution, stir for 4 h, let it stand for 2 h to separate layers, open the separation valve, and divide the lower sodium chloride aqueous solution into the crude sodium chloride tank. Transfer the upper crude isopropanol to the crude isopropanol storage tank. When the storage volume of the crude isopropanol accumulates to 3 t, pump the crude isopropanol into the adsorption system filled with HYA109 macroporous adsorption resin at a flow rate of 350 kg / h, collect the effluent, and obtain refined isopropanol. The content of odor substances (dimethyl disulfide, methyl sulfide, and methanethiol) in the refined isopropanol is detected by gas chromatography to be 13 ppm.

[0061] In the above example, when the storage volume of the crude dimethyl disulfide tank reaches 3000 L, transfer the crude dimethyl disulfide to the distillation kettle for distillation to obtain a dimethyl disulfide product with a purity greater than 95%.

[0062] Comparative Example 1

[0063] This comparative example provides a method for treating the recovered solvent in the preparation process of ametryn. Its preparation method is exactly the same as that of Example 1, except that HYA109 in Example 1 is replaced by HYA105, and it includes the following steps:

[0064] Add 335 kg of water to the isopropanol solvent recovered from the preparation process of 1000 kg of ametryn, stir for 2 h, let it stand for 1.5 h to separate layers, open the separation valve, and divide the lower oil layer into the crude dimethyl disulfide tank. Then, under stirring conditions, add 30 kg of sodium chloride to the remaining upper isopropanol aqueous solution, stir for 2 h, let it stand for 1 h to separate layers, open the separation valve, and divide the lower sodium chloride aqueous solution into the crude sodium chloride tank. Transfer the upper crude isopropanol to the crude isopropanol storage tank. When the storage volume of the crude isopropanol accumulates to 3 t, pump the crude isopropanol into the adsorption system filled with HYA105 macroporous adsorption resin at a flow rate of 300 kg / h, collect the effluent, and obtain refined isopropanol. The content of odor substances (dimethyl disulfide, methyl sulfide, and methanethiol) in the refined isopropanol is detected by gas chromatography to be 50 ppm.

[0065] Application Example

[0066] Add 1 ton of atrazine to 3 tons of the refined isopropanol prepared in Example 1, mix evenly, then add 1700 kg of sodium methyl mercaptide with a content of 20%, close the container and heat up to 120 °C, with a pressure of 0.3 MPa, keep the temperature for reaction for 5 h. After monitoring until the reaction ends, let it stand for stratification, separate the lower aqueous phase, distill out the isopropanol from the system, condense it, recycle it for use. Discharge the residue in the distillation kettle while it is hot, crush it to obtain the ametryn product. The product purity is 98.16%. According to the above gas chromatography, the content of odor substances (dimethyl disulfide, methyl sulfide and methyl mercaptan) in ametryn is 1.6 ppm.

[0067] Application comparative example

[0068] Add 1 ton of atrazine to 3 tons of the refined isopropanol prepared in Comparative Example 1, mix evenly, then add 1700 kg of sodium methyl mercaptide with a content of 20%, close the container and heat up to 120 °C, with a pressure of 0.3 MPa, keep the temperature for reaction for 5 h. After monitoring until the reaction ends, let it stand for stratification, separate the lower aqueous phase, distill out the isopropanol from the system, condense it, recycle it for use. Discharge the residue in the distillation kettle while it is hot, crush it to obtain the ametryn product. The product purity is 98.1%. According to the above gas chromatography, the content of odor substances (dimethyl disulfide, methyl sulfide and methyl mercaptan) in ametryn is 7 ppm.

[0069] In summary, the treatment method for recycling isopropanol in the ametryn production process provided by the present invention can effectively remove various odor substances contained in the isopropanol solvent, obtain isopropanol that can be recycled and dimethyl disulfide products with high added value. It not only solves the problem of the obvious malodorous smell of ametryn caused by the recycling and utilization of isopropanol, increases the market competitiveness of the product, but also realizes the resource utilization of waste, increases the enterprise income, and has high practical application value.

[0070] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements or improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for treating recycled solvents in the preparation process of ametryn, characterized in that, It includes the following steps: Step a: Add water to the recycled isopropanol solvent, mix evenly, let it stand, and separate the liquid to obtain a dimethyl disulfide oil phase and an isopropanol aqueous solution; distill the dimethyl disulfide oil phase to obtain a dimethyl disulfide product; Among them, the added amount of water is 1 / 3 - 2 / 3 of the mass of the recycled isopropanol solvent; Step b: Add sodium chloride to the isopropanol aqueous solution, mix evenly, let it stand, and separate the liquid to obtain a sodium chloride aqueous solution and crude isopropanol; the mass ratio of sodium chloride to the recycled isopropanol solvent is 0.03 - 0.05:1; Step c: Pass the crude isopropanol through HYA109 macroporous adsorption resin for adsorption to obtain refined isopropanol.

2. The method for treating the recovered solvent in the preparation process of ametryn as claimed in claim 1, wherein In step a, the standing time is 1h - 2h.

3. The method for treating the recycled solvent in the preparation process of ametryn as claimed in claim 1, characterized in that, In step b, the standing time is 1h - 2h.

4. The treatment method of the recycled solvent in the preparation process of ametryn as claimed in claim 1, characterized in that, In step c, the feeding flow rate of the crude isopropanol is 250 kg / h - 350 kg / h.

5. The treatment method of the recycled solvent in the preparation process of ametryn as described in claim 1, characterized in that, In step c, a multi-stage series HYA109 macroporous adsorption resin device is used for adsorption.

6. The treatment method of the recycled solvent in the preparation process of ametryn as claimed in claim 5, characterized in that, In step c, a two-stage series HYA109 macroporous adsorption resin device is used for alternating adsorption.

7. The treatment method of the recycled solvent in the preparation process of ametryn as claimed in claim 1, characterized in that, The recycled isopropanol solvent is prepared through the following process: Atrazine and sodium methyl mercaptide are subjected to a high-temperature reaction in an isopropanol solvent. After the reaction ends, oil-water separation is carried out, and the oil phase is distilled to obtain the recycled isopropanol solvent.

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